AN IDERARCHICAL DESCRIPTIVE CHECKLIST FOR CALCAREOUS
NANNOFOSSILSJackie A. Burnett & Paul R. Bown, Micropalaeontology Unit, Department of Geological Sciences,
University College London, Gower Street, LONDON, WCIE 6BT, U.K.
INTRODUCTION
Whilst discussing the application of coccolith terminology at the Terminology Workshop in London(April 8-10th, 1992), it became apparent that the terminology document (Young et al., in prep.) could
be summarised to produce a checklist for the standardisation of nannofossil descriptions. At present,
many nannofossil descriptions are ambiguous, even when accompanied by a photomicrograph! By
using a standard checklist each time a taxon is described, the description is made immediatelyintelligible to the reader (at whom it is aimed), and the systematic approach (using standard
terminology in a standard order) makes the description easier to translate into other languages,
promotes thoroughness whilst taking the strain off the author to remember to describe everything (ina logical order), and provides a standard format for database input.
So, below we have compiled a preliminary checklist, each section followed by a pro forma
example. This first draft, however, is meant as a prompt for comment. We would like a response tothe general idea, the format, the contents, anything you strongly disagree with, so that a checklist
could be produced and circulated that would be widely accepted and used. Please note, however, that
we do not wish to hear about terminology gripes (send those to Jeremy, if you must!). The purposeof this document is to define descriptive procedure only.
HIERARCHICAL DESCRIPTIVE CHECKLIST FOR NANNOFOSSILS
It may be worthwhile to consider making more use of schematic representation of the taxon being
described, i.e. instead of, or as well as, a written description, a comprehensively-labelled diagram(s)(or photo(s)) of the taxon could be incorporated. Graphic representation often conveys more meaning
than text and does not need to be translated, and so gives less scope for confusion. It is also
recommended (and we are not alone in thinking this) that we move away from describing taxa fromeither an SEM or LM photomicrograph. This approach promotes ambiguity and synonymy, and isnot as rigorously scientific as it should be. O.K., so you want the fame and fortune (!) that comeswith naming a new species, but perhaps first you should earn it by taking the time to provide avariety of good-quality photos. If you have not got the time or access to an SEM, why not ask
someone who has to help you out?
N.B. This checklist does not attempt to be utterly comprehensive. Also it is basically intended forfossil heterococcoliths. Descriptions of living species, holococcoliths or nannoliths would needmodified checklists.

1. BACKGROUND INFORMATION
The following headings are already widely used. It is suggested that they appear at the top of thedescriptive section, since they contain the most important data for the majority of database entries.
This list could be extended to include synonyms, paratypes etc.
1.1NAME
1.2 DERIVATION OF NAME
1.3 HOLOTYPE

1.4 TYPE LOCALITY
1.5 TYPE LEVELINA Newsletter, 14/3 - 1992

give full taxonomic citation according to rules of ICBN
not essential but, interesting, and aids memoryreference numbers and repository of holotype specimen. If
a photomicrograph, indicate whether LM, SEM or TEM,
distal, proximal or side viewgeographical source of holotype
lithostratigraphical horizon from which type sample wascollected1031.6 HOLOTYPE AGE

1.7 REMARKS

modern interpretation of age of horizon of holotype, withreference to chrono- &/or biostratigraphy. If possible givenanno zone.
specify whether coccolith (hetero-/holo-), nannolith, nannoconid
describe differences/similarities to related taxa
comment on preservationcomment on geographical/stratigraphical occurrence outside type locality, if known

E.g. Watznaueria barnesae (Black in Black & Barnes 1959) Perch-Nielsen 1968
Derivation of name: After Barbara Barnes, early nannopalaeontologist.
Holotype: No.3068, Sedgwick Museum, Cambridge University; Pl.9, fig.2 (TEM, proximal) in Black& Barnes (1959).
Type Locality: Weston Colville, Cambridgeshire, south-eastern England.
Type Level: English Chalk, Holaster planus macrofossil Zone
Holotype Age: Turonian, nannofossil zone CC12.
Remarks: This coccolith differs from W. jossacincta & W. ovata in having a closed or very small
central opening; from W. britannica & W. biporta in not possessing a bar spanning the central area;from W. manivitae in being smaller; & from W. quadriradiata in not possessing a central axial cross.
Very resistant to preservational effects, which can sometimes result in apparently monospecificassemblages.
Geographically & stratigraphically widespread, with a cosmopolitan occurrence from theBajocian (Middle Jurassic) to Maastrichtian (Late Cretaceous).

2. DESCRIPTION OF FOSSIL COCCOSPHERE
2.1 COCCOLITH DISTRIBUTION : monomorphic, dimorphic, polymorphic, varimorphic
monothecate, dithecate (define endothecal and exothecallayers), multilayered
2.2 COCCOSPHERE SHAPE
spherical, ovoid, ellipsoidal, cylindrical, fusiform,pyriform
2.3 APPROXIMATE NO. OF COCCOLITHS
2.4 COCCOLITH ARRANGEMENT :overlapping, non-overlapping, interlocking, non-interlocking
2.5 FLAGELLAR OPENING
presence/absence of possible flagellar opening, nature ofcircum-flagellar coccoliths.
E.g. Watznaueria barnesae (Black) Perch-Nielsen
A monomorphic, monothecate, spherical coccosphere with approximately 10, interlocking coccoliths.
No apparent flagellar opening.

3. DESCRIPTION OF HETEROCOCCOLITHS
3.1 DIAGNOSIS
3.1.1 RIMSIZE

OUTLINE

TYPE

104give size range in microns, and/or use descriptive terms very small, small, medium, large, very large (defined inYoung et al., in prep.)
give Axial Ratio, and/or use descriptive terms - circular,
subcircular, broadly/normally/ strongly elliptical, oblong,polygonal, reniform, asymmetricalbi-shield/tri-shield placolith, murolith, planoHth

INA Newsletter, 14/3 - 1992

piano-convex, concavo-convex, tapering, parallel-sided,
flaringlow, normal, high elevation
3.1.2 CENTRAL AREATYPESTRUCTURE

planiform, vaulted, conical, elevatedboss, blanket, plate, longitudinal/ transverse/diagonal bar,grill, net, axial/diagonal cross, foot, longitudinal/ diagonal/lateral arm, crossbar
spine - long/medium/short, tapering/ straight/flared,
with/without calyx.

E.g. Lotharingius crucicentralis (Medd) Grun & Zweili
Lotharingius crucicentralis coccoliths are small- to medium-sized, broadly elliptical, concavo-convex,
hi-shield placoliths with a central area spanned by a planiform axial cross & lateral arms, which may
support a medium-length, tapering spine.

3.2 DESCRIPTION OF RIM
3.2.1 ENTIRE RIM
VIEWCONSTRUCTION

3.2.2 EACH CYCLEELEMENT FORM
-SHAPE- MODIFICATIONSELEMENT RELATIONS- 1MBRICATION- IMBRICATION ANGLE- PRECESSION-CURVATURE
CRYSTALLOGRAPHYCRYSTAL ORIENTATION

distal, proximal; SEM, LM (Xp/PC/BF), TEM
outer/middle/inner/distal/proximal shield (cycle),outer/middle/inner tube (cycle), wall, flange, collar,crown, wing

tile, lath/petaloid lath/ray, rod, block, wedge
hole, node, keel, ridge, spine, tooth, slit, kink, perforation, depression, notchsinistral, non-imbricate, dextral
high; lowsinistral, radial, dextral
laevogyre, straight, dextrogyre
strongly /moderate! y/weakly /non- birefringent
isogyre appearance, sharp/diffuse
V, R, T units can be labelled on a diagram/
photomicrograph

E.g. Lotharingius crucicentralis (Medd) Grun & Zweili
In distal SEM view, the rim is composed of 3 visible cycles. The outermost cycle (distal shield cycle)
is the broadest, it is constructed from low-angle, dextrally-imbricate tiles joined along straight sutureswith sinistral precession. The middle cycle (middle tube cycle) is constructed from tiles withnear-radial, straight sutures. The innermost cycle (inner tube cycle) is constructed from tiles joined
along radial & vertical sutures.
In proximal SEM view, the proximal shield can be seen to be slightly smaller than the .jistal
shield, & is composed of only 1 cycle (proximal shield cycle), formed from non-imbricate, kinkedtiles, joined along sutures with laevogyre curvature & sinistral precession. Detailed SEM analysis has
shown that the distal shield, inner tube and proximal shield cycles form a single crystal-unit.
In the LM (Xp), the rim appears strongly birefringent & is crossed by sharp isogyres. The distal
shield/ inner tube/proximal shield cycle crystal-unit is birefringent, and has been interpreted as anR-unit (Young & Bown 1991). The middle tube cycle is weakly/non-birefringent and has beeninterpreted as a V-unit. In the LM (PC), the coccolith is bright.

INA Newsletter, 14/3 - 1992105

3.3 DESCRIPTION OF CENTRAL AREA
VIEW
RELATIVE WIDTHOUTLINECENTRAL STRUCTURE-POSITION- CONSTRUCTION-TYPE- CRYSTALLOGRAPHY

distal, proximal; SEM, LM (Xp/PC/BF), TEM
wide, normal, narrowcircular, subcircular, broadly/normally/ strongly elliptical,
oblong, polygonal, reniform, asymmetricalopen, closed
basal, elevatedcompound, simple, disjunct, conjunctboss, blanket, plate, longitudinal/ transverse/diagonal bar,grill, net, axial/diagonal cross, foot, longitudinal/lateral/diagonal arm, crossbarspine- tapering/straight/flared with/without calyx; blocky/granular/lath-like, hollow/solid, long/medium/short stem
description of elements (same terms as for rim elements)
strongly /moderate! y/weakly /non- birefringent

E.g. Lotharingius crucicentralis (Medd) Grun & Zweili
In distal SEM view, the central area is wide, broadly elliptical & open. It is spanned by a basal,
disjunct, compound, axial cross with 3-4 lateral arms in each open quadrant. The cross may support
a medium-length, tapering, compound spine, with no calyx.
In the LM (Xp), the cross is birefringent when orientated parallel to the polarising direction. The
lateral arms are usually weakly/non-birefringent.

ACKNOWLEDGEMENTS
This manuscript benefitted from discussions with Jeremy Young (NHM) and, generally, with theparticipants of the Terminology Workshop. JAB acknowledges the support of the NERC.
REFERENCES
Black M. & Bames B. 1959: The structure of coccoliths from the English chalk. Geol. Mag., 96, 321-328.
Bown P.R. 1987: Taxonomy, evolution and biostratigraphy of Late Triassic -Early Jurassic calcareous nannofossils. Spec.
Pap. Palaeont., 38, 1-118.
Perch-Nielsen K. 1968: Der Feinbau und die Klassification der Coccolithen aus dem Maastrictien- und Danienlokalitiiten. Bioi.
Skr. K. Danske Vidensk. Selsk., 16, 1-96.
Young, J.R. & Bown, P.R., 1991: An ontogenetic sequence of coccoliths from the late Jurassic Kimmeridge Clay of England.
Palaeontology, 34, 843-850.
Young J.R. et al (in prep): Guidelines for cocolith and calcreous nannofossil terminology. Palaeontology (provisionallyaccepted).

106

INA Newsletter, 14/3 - 1992